JP2021082496A - Mass spectroscope - Google Patents

Abstract

To provide a mass spectroscope in which maintenance of ion optical elements such as a quadrupole mass filter can be easily performed while maintaining high mounting accuracy and the like.SOLUTION: A mass spectroscope includes: a vacuum chamber 10 in which a vacuum chamber is formed, one of left and right sides of the vacuum chamber which face each other through an ion optical axis in the vacuum chamber being openable and closable; an ion optical element 21 that performs a predetermined operation on ions derived from a sample; a pedestal portion 33 that is placed on a bottom surface of the vacuum chamber and on which the ion optical element is placed; a thin plate-shaped fixing band 213 that fixes the ion optical element so as to be pressed against the pedestal portion by putting a part of the ion optical element between the pedestal portion and itself; a band locking portion 10d that is provided inside a side wall surface of the vacuum chamber on an opposite side to the openable and closable side surface of the vacuum chamber and locks one end of the fixing band; and a band fixing portion 214 that is provided on the openable and closable side surface side of the vacuum chamber at the pedestal portion and fixes the other end of the fixing band to the pedestal portion.SELECTED DRAWING: Figure 3

Description

The present invention relates to a mass spectrometer. The present invention is suitable for a mass spectrometer in which a quadrupole mass filter and a collision cell are arranged in an analysis chamber having a high degree of vacuum.

In a general quadrupole mass analyzer, ions are generated from the compounds contained in the sample at the ion source, and the various ions generated are separated by a quadrupole mass filter according to the mass-to-charge ratio m / z. Then, the separated ions are detected by an ion detector. In addition, in a triple quadrupole mass analyzer in which quadrupole mass filters are arranged in front of and behind a collision cell, various ions generated by an ion source are converted to a mass-to-charge ratio by the quadrupole mass filter in the previous stage. Correspondingly, only ions having a specific mass-to-charge ratio (precursor ions) are selectively introduced into the collision cell. Then, in the collision cell, precursor ions are dissociated by a method such as collision-induced dissociation (CID), and various product ions generated by the dissociation are separated according to the mass-to-charge ratio by a quadrupole mass filter in the subsequent stage, and the ions are separated. The product ion is detected by an ion detector.

In such a mass spectrometer, neutral particles and ions derived from a sample adhere to ion optical elements such as a rod electrode constituting a quadrupole mass filter and a rod electrode arranged in a collision cell during analysis. Therefore, when the device is used for a long time, the ion optical elements are contaminated, and the electric field generated by them is disturbed. As a result, performance deterioration such as deterioration of detection sensitivity and mass accuracy occurs. Therefore, if the performance of the device becomes unstable due to contamination of the ion optical element, etc., maintenance work such as removing the quadrupole mass filter unit and collision cell from the device and cleaning them is required. is there. In a conventional general mass spectrometer, a lid that can be opened and closed is provided at the top of the vacuum chamber so that such maintenance work can be easily performed, and the quadrupole mass filter or collision cell is raised with the lid open. It has a structure that allows it to be removed in the direction or attached from above (see Patent Document 1).

A liquid chromatograph mass spectrometry (LC-MS) system using the above-mentioned mass spectrometer as a liquid chromatograph (LC) detector generally includes a detector unit and a pump for feeding a mobile phase. It is composed of a plurality of units such as a liquid feeding unit containing the liquid, an injection unit for injecting a sample into the fed mobile phase, and a column oven unit containing a column. Since the conventional general mass spectrometer is considerably larger in size than the units other than the detector unit, it is installed separately from those units. Therefore, the LC-MS system requires a relatively large installation space.

However, as the fields of use of LC-MS systems have expanded, there has been a strong demand for reducing the installation space of the system, and in recent years, compared to conventional general quadrupole mass spectrometers. A considerably smaller device has been developed. For example, in the LC-MS system disclosed in Non-Patent Document 1, the detector unit, which is a mass spectrometer, is suppressed to the same size as other units, and a system configuration in which other units are stacked becomes possible. ing.

International Publication No. 2019/155543

"ACQUITY QDa Detector-Mass Spectrometry (MS) Detector", [online], Japan Waters Corp., [Search October 29, 2019], Internet <URL: http://www.waters.com/waters/ ja_JP / ACQUITY-QDa-Mass-Detector-for-Chromatographic-Analysis / nav.htm? Locale = ja_JP & cid = 134761404 ＞

However, such a miniaturized mass spectrometer has the following problems.
That is, since the detector unit, which is a mass spectrometer, includes a vacuum chamber made of stainless steel or the like, a vacuum pump, or the like, the weight is heavier than other units constituting the LC-MS system. Therefore, when stacking a plurality of units, it is generally installed at the bottom. In an LC-MS system with such a configuration, if maintenance of the quadrupole mass filter of the detector unit is to be performed, it is necessary to move the unit mounted on the upper part of the detector unit, and the maintenance work is very complicated. There is a problem that it takes time.

The present invention has been made to solve the above problems, and an object of the present invention is to stack other devices such as a unit constituting an LC-MS system on the mass spectrometer. Even in this case, it is an object of the present invention to provide a mass spectrometer capable of easily performing maintenance of an ion optical element such as a quadrupole mass filter while maintaining high mounting accuracy and the like.

One aspect of the mass spectrometer according to the present invention made to solve the above problems is
A vacuum chamber in which a vacuum chamber is formed and one of the left and right sides can be opened and closed across the ion optical axis in the vacuum chamber.
An ion optical element that performs a predetermined operation on the ions derived from the sample,
A pedestal portion arranged on the bottom surface of the vacuum chamber and on which the ion optical element is placed,
A thin plate-shaped fixing band for sandwiching at least a part of the ion optical element between the pedestal portion and fixing the ion optical element so as to be pressed against the pedestal portion.
A band locking portion for locking one end of the fixing band provided inside the side wall surface of the vacuum chamber opposite to the openable / closable side surface of the vacuum chamber.
A band fixing portion for fixing the other end of the fixing band to the pedestal portion, which is provided on the openable side surface side of the vacuum chamber in the pedestal portion.
Is provided.

In the above aspect of the mass spectrometer according to the present invention, the ion optical element includes, for example, a quadrupole mass filter, an ion guide, an ion lens, an ion trap, a deflector, a reflector and the like that control the behavior of ions by the action of an electric field. .. Further, the ion optical element shall also include a collision cell or the like that provides a space for dissociating ions.

In the above aspect of the mass spectrometer according to the present invention, for example, an elongated vacuum chamber is arranged so as to extend in the front-rear direction. In this case, the ion optical axis is also extended in the front-rear direction in the vacuum chamber in the vacuum chamber, and the side surface of either the left or right vacuum chamber sandwiching the ion optical axis can be opened and closed. When the target ion optical element is taken out of the apparatus, the operator opens the side surface of the vacuum chamber. Then, since there is a band fixing portion on the front side of the ion optical element when viewed from the opening of the vacuum chamber, the fixing of this fixing portion is released. The band fixing portion may be fixed by using another member such as a screw.

On the other hand, on the other side of the ion optical element when viewed from the opening of the vacuum chamber, the fixed band is only locked by the band locking portion. Therefore, unlike the band fixing portion, the operator can easily remove the fixing band without performing work such as removing the screw. Then, after removing the fixing band, the ion optical element may be removed from above the pedestal and taken out of the device through the opening. When the ion optical element is attached to the inside of the apparatus, the procedure may be the reverse of the above removal operation.

According to one aspect of the mass spectrometer according to the present invention, the ion optical element can be attached and detached from the side of the apparatus. As a result, the maintenance work of the ion optical element can be performed while the other device is mounted on the upper part of the device, that is, without moving the other device, and high workability is achieved. It can be realized. Further, since the ion optical element can be easily attached and detached by tightening or removing the screw on the front side of the ion optical element, not only the work of attaching and detaching the ion optical element can be efficiently performed, but also the work of attaching and detaching the ion optical element can be performed efficiently. It is possible to prevent accidents such as damage to the ion optical element due to contact with a tool or the like. Furthermore, the ion optical element can be accurately mounted at an appropriate position with a simple operation.

The external perspective view of the LC-MS system using the mass spectrometer of the 1st Embodiment of this invention. The block diagram of the main part of the mass spectrometer of 1st Embodiment. A schematic vertical sectional view of the mass spectrometer of the first embodiment as viewed from the front. The schematic plan view of the mass spectrometer of 1st Embodiment in the state which removed the right side cover. The schematic plan view of the mass spectrometer of 1st Embodiment in the state which removed the right side cover and the vacuum chamber side cover. Schematic vertical cross-sectional view of the mass spectrometer of the second embodiment of the present invention as viewed from the front. The schematic plan view of the mass spectrometer of the 2nd Embodiment in the state which removed the right side cover. The schematic plan view of the mass spectrometer of the 2nd Embodiment in the state which removed the right side cover and the vacuum chamber side cover. The schematic horizontal sectional view which shows the ion gauge mounting structure in the mass spectrometer of 1st Embodiment. The perspective view of the part used for the ion gauge mounting structure in the mass spectrometer of 1st Embodiment.

[First Embodiment]
The mass spectrometer according to the first embodiment of the present invention will be described with reference to the accompanying drawings.
This mass spectrometer is a single-type quadrupole mass spectrometer equipped with an atmospheric pressure ion source such as an electrospray ionization (ESI) method.

FIG. 1 is an external perspective view of an LC-MS system using the mass spectrometer of the first embodiment as a detector. This LC-MS system includes a mass spectrometer 1 which is a detector unit, a column oven unit 2, two liquid feeding units 3 and 4, and an injection unit 5. The liquid feeding units 3 and 4 include a mobile phase container containing a mobile phase, a liquid feeding pump, a mixer and the like. The injection unit 5 includes an autosampler, an injector, and the like. The column oven unit 2 includes a column inside. The outer shape of each unit is substantially rectangular, and as shown in FIG. 1, the units can be used in a stacked state. For convenience of explanation, as shown in the figure, the X-axis, the Y-axis, and the Z-axis that are orthogonal to each other are defined. That is, the Z-axis direction is the height direction, and the Y-axis direction is the depth direction.

FIG. 2 is a block diagram of a main part of the mass spectrometer 1. The inside of the vacuum chamber 10 is divided into three chambers, a first intermediate vacuum chamber 11, a second intermediate vacuum chamber 12, and a high vacuum chamber 13. Further, in front of the vacuum chamber 10, an ionization unit defining an ionization chamber 14 is attached inside. The first intermediate vacuum chamber 11, the second intermediate vacuum chamber 12, and the high vacuum chamber 13 are each evacuated by a vacuum pump (not shown), and the ionization chamber 14 communicates with the outside.

An ionization probe 15 is provided in the ionization chamber 14, and the ionization chamber 14 and the first intermediate vacuum chamber 11 communicate with each other through a small-diameter desolvation tube 16. A first ion guide 17 is arranged inside the first intermediate vacuum chamber 11, and the first intermediate vacuum chamber 11 and the second intermediate vacuum chamber 12 communicate with each other through a small hole formed at the top of the skimmer 18. A second ion guide 19 is arranged inside the second intermediate vacuum chamber 12, and the second intermediate vacuum chamber 12 and the high vacuum chamber 13 communicate with each other through a small hole formed in the center of the lens electrode 20. Inside the high vacuum chamber 13, a quadrupole mass filter 21 including a pre-rod electrode and a main rod electrode, and an ion detector 22 are arranged.

As shown in FIG. 2, the desolvation tube 16, the first ion guide 17, the skimmer 18, the second ion guide 19, the lens electrode 20, the quadrupole mass filter 21, and the ion detector 22 are substantially linear ions. It is arranged along the optical axis C.

The analysis operation in the LC-MS system will be briefly described.
The liquid feeding units 3 and 4 feed the mobile phase, which is a single liquid or a mixture of two liquids, to the column at a predetermined flow rate (flow rate). The injection unit 5 selects one from a plurality of samples prepared in advance, sucks it, and injects it into the mobile phase fed to the column at a predetermined timing. In the column oven unit 2, the column is maintained at, for example, a substantially constant temperature. When a sample is introduced into the column by being pushed by the flow of the mobile phase, various components (compounds) contained in the sample are separated in time while passing through the column. Then, the eluate containing the separated components is eluted from the outlet of the column and introduced into the ionization probe 15 of the mass spectrometer 1.

The ionization probe 15 sprays the eluate into the ionization chamber 14 having a substantially atmospheric pressure atmosphere, and ionizes the sample components contained in the eluate. As the ionization method, for example, an electrospray ionization method or an atmospheric pressure chemical ionization method can be used. The generated ions are sent into the first intermediate vacuum chamber 11 through the desolvation tube 16, and further sent to the high vacuum chamber 13 via the first ion guide 17, the skimmer 18, the second ion guide 19, and the lens electrode 20. Be done. Ions derived from this sample component are introduced into the quadrupole mass filter 21, and only ions having a specific mass-to-charge ratio corresponding to the voltage applied to the rod electrodes constituting the quadrupole mass filter 21 are quadrupole. It passes through the mass filter 21 and the other ions are emitted on the way. The ion detector 22 detects ions that have passed through the quadrupole mass filter 21 and outputs a detection signal according to the amount of the ions.

In this way, in this LC-MS system, after separating a plurality of components contained in the sample in the time direction, the mass spectrometer 1 can obtain a detection signal according to the amount (concentration) of each component. it can. As described above, inside the vacuum chamber 10 of the mass spectrometer 1, the ions derived from the sample components travel from the front side to the rear side of the device, that is, substantially in the Y-axis direction.

As already described, when the analysis is performed, the quadrupole mass filter 21, the ion guides 17, 19 and other ion optical elements include ions derived from sample components, neutral particles such as non-ionized molecules, or solvent molecules. Adheres and becomes dirty. Therefore, it is necessary to take out such an ion optical element from the inside of the vacuum chamber 10 and clean it. However, a column oven unit 2 (or other unit for a liquid chromatograph) is placed on the upper part of the mass spectrometer 1, and it is troublesome to move this for maintenance work. Therefore, the mass spectrometer 1 of the present embodiment has a characteristic structure as described below.

FIG. 3 is a schematic vertical sectional view of the mass spectrometer of the present embodiment as viewed from the front. FIG. 4 is a schematic plan view of the mass spectrometer of the present embodiment with the right side cover removed. FIG. 5 is a schematic plan view of the mass spectrometer of the present embodiment with the right side cover and the vacuum chamber side cover removed.

As shown in FIGS. 3 and 4, in the mass spectrometer 1 of the present embodiment, the vacuum chamber 10 extends along the Y-axis direction immediately inside the right side cover 30a of the substantially rectangular exterior cover 30. It is arranged like this. The right side cover 30a is attached to other parts of the exterior cover 30 with screws or the like, and the right side cover 30a can be easily removed by removing the screws or the like.

A vacuum pump unit 32 is arranged in the lower part of the vacuum chamber 10, and a circuit unit 31 including various electrical components is arranged in the upper part and the left side of the vacuum chamber 10. An opening is formed on the right side of the portion of the high vacuum chamber 13 formed in the vacuum chamber 10, that is, the portion on the rear side of the vacuum chamber 10, and the side lid 10a can be attached and detached so as to cover the opening. It is provided. The side lid 10a can also be attached by screws or the like. When the side lid 10a is attached, the inside of the high vacuum chamber 13 becomes substantially airtight, and vacuum exhaust by a vacuum pump becomes possible.

When the right side cover 30a is removed from the exterior cover 30 as shown in FIG. 3, almost the entire right side is opened as shown in FIG. 4, so that the right side of the vacuum chamber 10 is exposed. When the side lid 10a is removed from the vacuum chamber 10 with the vacuum in the vacuum chamber 10 released, the quadrupole mass filter 21 and the ion detector arranged in the high vacuum chamber 13 are arranged as shown in FIG. 22 is exposed. Therefore, the operator performing the maintenance can easily access the members arranged in the high vacuum chamber 13 by removing the right side cover 30a and the side lid 10a, respectively.

The four main rod electrodes 211 constituting the quadrupole mass filter 21 having a substantially cylindrical outer shape are each fitted in a groove inside a rod holder 212 having a substantially annular shape and a predetermined thickness. , It is fixed to the rod holder 212 by a screw (not shown). One rod holder 212 is provided on each of the front end side and the rear end side of the main rod electrode 211, whereby the relative positional relationship between the four main rod electrodes 211 is determined. Further, although the description is omitted in FIG. 5, the four pre-rod electrodes are attached in front of each of the four main rod electrodes 211 with an insulator interposed therebetween. The rod electrode 211 is made of a conductor such as stainless steel or molybdenum, and the rod holder 212 is made of an insulator such as ceramic or synthetic resin.

Each of the two rod holders 212 is placed in a substantially semicircular recess 33a of the pedestal portion 33 mounted on the bottom surface of the vacuum chamber 10. That is, the lower portion of the rod holder 212 is housed in the recess 33a of the pedestal portion 33. The upper portion of the rod holder 212 is fixed by a spring-loaded fixing band 213 so as to be pressed downward, that is, against the recess 33a of the pedestal portion 33. One end of the fixing band 213 is locked by a locking portion 10d which is a recess formed inside the left side wall 10c of the vacuum chamber 10, and the other end of the fixing band 213 is fixed to the pedestal portion 33 with a screw 214. Will be done. As a result, the four main rod electrodes 211 are surely installed at predetermined positions.

The pedestal 33 is made of the same material as the vacuum chamber 10, such as aluminum or stainless steel. Further, the fixing band 213 may be made of, for example, stainless steel or phosphor bronze having a rust-preventive surface treatment. Further, as shown in FIG. 3, the distance L between the upper surface of the pedestal portion 33 and the top surface of the vacuum chamber 10 is set to be larger than the outer diameter D of the rod holder 212.

As described above, the end of the fixing band 213 located on the side beyond the main rod electrode 211 when viewed from the right side of the vacuum chamber 10 is simply inserted into the locking portion 10d and locked. is there. On the other hand, the end of the fixing band 213 fixed by the screw 214 is located on the front side of the main rod electrode 211 when viewed from the right side of the vacuum chamber 10. Therefore, the fixing band 213 can be easily pulled out from the locking portion 10d as long as the operator removes the side lid 10a and then removes the screw 214 in front of the side lid 10a as described above. Since the relationship is L> D as described above, after removing the fixing band 213, the rod holder 212 holding the main rod electrode 211 is lifted from the pedestal portion 33 and moved to the front side as it is to create a vacuum. It can be taken out of the chamber 10. That is, the quadrupole mass filter 21 can be easily taken out of the device while avoiding contact between the main rod electrode 211 and the pedestal portion 33.

Further, when the quadrupole mass filter 21 once removed is installed in the vacuum chamber 10, the quadrupole mass filter 21 can be easily and appropriately attached at an appropriate position by the reverse procedure of the above.

As described above, since the fixing band 213 fixes the rod holder 212 so as to press it against the pedestal portion 33, an appropriate spring property is required. Since stainless steel has a relatively large Young's modulus, it is advantageous in terms of springiness. On the other hand, phosphor bronze has a smaller Young's modulus than stainless steel, but by adjusting the thickness, it can have the same springiness as a stainless steel fixing band. In addition, phosphor bronze has a higher thermal conductivity than stainless steel. As described in Patent Document 1 and the like, when a high frequency voltage is applied to the main rod electrode 211 during analysis, the rod holder 212 itself generates heat due to the dielectric loss of the material of the rod holder 212. On the other hand, by using phosphor bronze as the fixing band 213 and keeping its thermal conductivity good, the heat of the rod holder 212 is conducted to the pedestal portion 33 through the fixing band 213, and the pedestal portion 33 to the vacuum chamber 10 It becomes easy to escape to such as. As a result, heat dissipation from the rod holder 212 can be promoted, and misalignment of the main rod electrode 211 due to thermal expansion of the rod holder 212 can be prevented.

Although the description of the structure such as the wiring for applying the voltage to the four main rod electrodes 211 is omitted in FIGS. 3 and 5, for example, the main rod as disclosed in Patent Document 1. A structure can be adopted in which a predetermined voltage is applied to each main rod electrode via a short spring that elastically contacts the rod electrode. Of course, the structure for applying the voltage is not limited to this.

As described above, according to the mass spectrometer of the present embodiment, the operator can easily access the inside of the vacuum chamber 10 from the right side of the device, and the quadrupole mass filter installed inside the vacuum chamber 10 The 21 can be easily taken out, or conversely, the quadrupole mass filter 21 can be easily mounted inside the vacuum chamber 10. As a result, it is not necessary to move another unit mounted on the mass spectrometer 1 during the maintenance work. Further, since the work itself of attaching and detaching the quadrupole mass filter 21 is simple and does not take time, the work can be performed efficiently.

Of course, not only the quadrupole mass filter 21 but also other ion optical elements such as the ion guides 17 and 19 can have the same configuration. However, the ion optical elements such as the ion guides 17 and 19 located on the upstream side of the ion flow can be structurally configured to be pulled out to the front side of the device. On the other hand, it is quite difficult to configure the quadrupole mass filter 21 located on the downstream side of the ion flow, the collision cell described later, and the like to be pulled out to the front side of the device. For these reasons, the configuration in which the device can be attached and detached from the side is particularly advantageous for the ion optical element located on the rear side of the device.

Further, the first embodiment described above is an example in which the present invention is applied to a single type quadrupole mass spectrometer, but the present invention is an example of another type of mass spectrometer, specifically, a triple quadrupole mass spectrometer. It can also be applied to a type mass spectrometer and the like. The triple quadrupole mass spectrometer has a quadrupole mass filter in front of and behind the collision cell. It goes without saying that the quadrupole mass filters before and after this can be configured as described above, but the same configuration can be adopted for the collision cell.

[Second Embodiment]
Next, the triple quadrupole mass spectrometer according to the second embodiment of the invention according to the present invention will be described with reference to FIGS. 6 to 8. FIG. 6 is a schematic vertical sectional view of the mass spectrometer of the second embodiment as viewed from the front. FIG. 7 is a schematic plan view of the mass spectrometer of the second embodiment with the right side cover removed. FIG. 8 is a schematic plan view of the mass spectrometer of the second embodiment with the right side cover and the vacuum chamber side cover removed. That is, FIGS. 6 to 8 are drawings corresponding to FIGS. 3 to 5 in the first embodiment. In this second embodiment, the same or corresponding components as those of the mass spectrometer of the first embodiment described above are designated by the same reference numerals.

As shown in FIG. 8, a front quadrupole mass filter 40 and a rear quadrupole mass filter 42 are arranged in the high vacuum chamber 13 with the collision cell 41 interposed therebetween. The collision cell 41 has a cell body 410 having a substantially cylindrical shape and ion passage openings formed on both end surfaces thereof, and four rod electrodes 411 constituting an ion guide are arranged inside the cell body 410. There is. The number of rod electrodes constituting the ion guide is not limited to this. A collision-induced dissociation gas, which is a predetermined inert gas, is introduced into the cell body 410, and ions that have passed through the pre-stage quadrupole mass filter 40 come into contact with the collision-induced dissociation gas inside the cell body 410 and dissociate. To do. The product ions generated by the dissociation are converged by the electric field generated by the high frequency voltage applied to the rod electrode 411 and sent out to the subsequent quadrupole mass filter 42.

In the mass spectrometer of the second embodiment, similarly to the front quadrupole mass filter 40 and the rear quadrupole mass filter 42, the cell body 410 of the collision cell 41 can be easily attached and detached by the pedestal 33 and the fixed band 213. It is fixed. Therefore, when cleaning the collision cell 41, the operator removes the right side cover 30a and the side lid 10a, respectively, makes the inside of the high vacuum chamber 13 accessible, and then fixes the fixing band 213. The collision cell 41 can be easily taken out of the vacuum chamber 10 by removing the screw 214.

[Ion gauge mounting structure]
In the mass spectrometers of the first and second embodiments, an ion gauge 35 for measuring the degree of vacuum in the high vacuum chamber 13 is attached to the back surface of the rear wall 10e of the vacuum chamber 10. Since the ion gauge 35 has a filament and is a consumable item, it is preferable that the ion gauge 35 can be replaced as easily as possible. Generally, the back plate of the exterior cover is made removable, and the ion gauge can be removed by removing the screw or the like fixing the ion gauge from the rear side. However, the LC-MS system as shown in FIG. 1 is often installed so that its back surface is close to the wall, and it is difficult to access from the rear side. Therefore, the mass spectrometers of the first and second embodiments adopt a structure in which the ion gauge 35 can be easily attached and detached from the right side.

FIG. 9 is a schematic horizontal sectional view showing an ion gauge mounting structure in the mass spectrometer of the first embodiment, and FIG. 10 is a perspective view of parts used for the ion gauge mounting structure in the mass spectrometer of the first embodiment. ..

A mounting hole 10f is provided through the rear wall 10e of the vacuum chamber 10, and a connecting pipe portion 35a communicating with the internal space of the ion gauge 35 is inserted into the mounting hole 10f. The parts for mounting the ion gauge 35 in the mounting hole 10f are a first plate-shaped member 350 having a substantially U shape, an annular spacer 351 for adjusting the mounting height of the first plate-shaped member 350, and a first. A bolt 352 for hooking one plate-shaped member 350, a cylindrical flange 353 with a step, a gasket retainer 354 which is substantially annular, two annular gaskets 355 made of rubber, and a first plate-shaped member. A second plate-shaped member 356 that locks both ends of the member 350, an annular spacer 357 that adjusts the mounting height of the second plate-shaped member 356, and a screw 358 for fixing the second plate-shaped member 356. And, including.

As shown in FIG. 9, a gasket 55, a gasket retainer 354, and a flange 353 are inserted into the connecting pipe portion 35a of the ion gauge 35 from the tip end side thereof. When the connecting pipe portion 35a is fitted into the mounting hole 10f, the gasket 355 is positioned in contact with the stepped portion formed on the inner circumference of the mounting hole 10f. The bolt 352 is screwed into the bolt hole of the rear wall 10e of the vacuum chamber 10 with the spacer 351 inserted. The first plate-shaped member 350 is mounted so as to sandwich the spacer 351 between the rear wall 10e and the bolt 352 and the flange 353 between both the U-shaped extending portions. Since the U-shaped extension portion of the first plate-shaped member 350 is formed in a curved shape along the outer peripheral shape of the flange 353, the first plate-shaped member 350 is inserted until the curved portion abuts on the flange 353. To do.

On the other hand, the second plate-shaped member 356 is fixed to the rear wall 10e by three screws 358 in a state where the spacer 357 is sandwiched between the spacer 357 and the rear wall 10e. When the screw 358 is tightened, the second plate-shaped member 356 presses the end of the U-shaped extension portion of the first plate-shaped member 350, and the first plate-shaped member 350 is flanged so as to sink into the mounting hole 10f. Push down 353. Then, the flange 353 pushes down the gasket 355 via the gasket retainer 354. Since the gasket 255 is made of rubber and its position is restricted, it is crushed by receiving a force and comes into close contact with the inner peripheral surface of the mounting hole 10f and the outer peripheral surface of the connecting pipe portion 35a of the ion gauge 35. As a result, the ion gauge 35 can be attached while ensuring the airtightness in the high vacuum chamber 13.

When removing the ion gauge 35 for replacement of the ion gauge 35 or the like, the operator loosens the screw 358 from the right side of the device using a tool such as an offset screwdriver. Then, the restraint of the first plate-shaped member 350 is released and the gasket 355 is restored, so that the connecting pipe portion 35a of the ion gauge 35 can be easily pulled out from the mounting hole 10f. This makes it possible to easily remove the ion gauge 35 from the right side of the device. When attaching the ion gauge 35, the work may be performed in the reverse procedure of the removal.
In this way, the ion gauge 35 can be easily attached to and detached from the right side of the mass spectrometer 1.

Further, the above embodiment is only an example of the present invention, and it is clear that the present invention is included in the claims even if it is further appropriately modified, added, or modified within the scope of the present invention.

[Various aspects]
It will be understood by those skilled in the art that the above-described exemplary embodiments are specific examples of the following embodiments.

(Section 1) One aspect of the mass spectrometer according to the present invention is
A vacuum chamber in which a vacuum chamber is formed and one of the left and right sides can be opened and closed across the ion optical axis in the vacuum chamber.
An ion optical element that performs a predetermined operation on the ions derived from the sample,
A pedestal portion arranged on the bottom surface of the vacuum chamber and on which the ion optical element is placed,
A thin plate-shaped fixing band for sandwiching at least a part of the ion optical element between the pedestal portion and fixing the ion optical element so as to be pressed against the pedestal portion.
A band locking portion for locking one end of the fixing band provided inside the side wall surface of the vacuum chamber opposite to the openable / closable side surface of the vacuum chamber.
A band fixing portion for fixing the other end of the fixing band to the pedestal portion, which is provided on the openable side surface side of the vacuum chamber in the pedestal portion.
Is provided.

In the mass spectrometer according to the first item, the side surface of the vacuum chamber can be opened instead of the upper surface (top surface), and when this side surface is opened, the band fixing portion is located on the front side of the ion optical element. .. Then, on the other side of the ion optical element when viewed from the opening of the vacuum chamber, the fixed band is only locked by the band locking portion. Therefore, the fixing band can be easily removed by simply releasing the fixing by the band fixing part on the front side, and after removing the fixing band, the ion optical element can be removed from the top of the pedestal and taken out to the outside of the device. it can.

As described above, according to the mass spectrometer described in the first paragraph, the ion optical element remains in a state where another device is mounted on the upper part of the device, that is, without moving the other device. Maintenance work can be performed, and high workability can be realized. Further, since the work itself of attaching and detaching the ion optical element is simple and does not take time and effort, the maintenance work can be performed efficiently. In addition, it is possible to prevent accidents such as damage to the ion optical element due to contact with a tool or the like. Furthermore, the ion optical element can be accurately mounted at an appropriate position with a simple operation.

(Item 2) In the mass spectrometer according to the item 1, the ion optical element has four rod electrodes arranged around a linear axis and an insulating property that holds the four rod electrodes. It is a quadrupole mass filter including a rod holder made of a material, and the fixing band can be attached so as to press the rod holder against the pedestal portion.

According to the mass spectrometer according to the second item, even if the quadrupole mass filter that separates ions according to the mass-to-charge ratio becomes dirty, it can be relatively easily removed and washed.
Also, in many cases, the quadrupole mass filter is located downstream of the ion stream in the path of sample-derived ions in the mass spectrometer. Therefore, in a device in which an ion source is provided on the front side of the device and the ions generated by the ion source are sent to the rear side of the device, the quadrupole mass filter is arranged on the rear side of the device. In such a case, it is difficult to adopt a structure in which the quadrupole mass filter can be removed by pulling it out to the front of the device. On the other hand, according to the mass spectrometer described in the second paragraph, since the quadrupole mass filter can be removed on the side of the device, the workability of maintenance of the quadrupole mass filter is improved.

(Item 3) In the mass spectrometer according to the first item, the ion optical element is a collision cell including a cell body portion for dissociating ions, and the fixed band has the cell body portion on the pedestal portion. It can be attached so as to hold it down.

According to the mass spectrometer according to the third item, even if the cell body of the collision cell for dissociating the ions or the ion guide arranged inside the cell body becomes dirty, it can be removed relatively easily. Can be washed. Further, like the quadrupole mass filter, the collision cell is also located downstream of the ion flow and is often arranged on the rear side of the device, but even in that case, it is easy to attach and detach.

That is, the ion optical element in the mass spectrometer according to the present invention may be an ion optical element located anywhere in the ion path, but particularly in the latter part of the ion path, that is, downstream of the ion flow. It can be said that the effect is great for the ionic optical element located.

(Item 4) In the mass spectrometer according to item 2, the distance between the inside of the top surface of the vacuum chamber and the upper surface of the pedestal portion is larger than the outer diameter of the rod holder which is annular. Can be.

(Clause 5) In the mass spectrometer according to the third item, the distance between the inside of the top surface of the vacuum chamber and the upper surface of the pedestal portion is larger than the outer diameter of the cell body portion which is cylindrical. Can be.

According to the mass spectrometers described in the fourth and fifth paragraphs, the quadrupole mass filter and the collision cell can be lifted from the pedestal portion and taken out of the vacuum chamber as they are with the fixing band removed. Further, the quadrupole mass filter and the collision cell can be taken in and out without contacting the pedestal portion and the top surface of the vacuum chamber. Therefore, the work of attaching and detaching the quadrupole mass filter and the collision cell can be easily performed, and it is possible to prevent them from coming into contact with the pedestal portion and the top surface of the vacuum chamber and being damaged.

(Section 6) In the mass spectrometer according to any one of paragraphs 1 to 5, the vacuum chamber is arranged so that its openable side surface faces the side surface of the exterior cover. Can be.

In the mass spectrometer according to item 6, when the side surface of the exterior cover is opened, there is a vacuum chamber immediately inside, and when the side surface of the vacuum chamber is opened, the ion optical element can be attached and detached. Therefore, according to the mass spectrometer according to the sixth item, the attachment / detachment of the ion optical element is easier.

(Section 7) In the mass spectrometer according to any one of paragraphs 1 to 6, a flat portion on which another device can be placed is formed on the upper surface of the exterior cover. can do.

In the mass spectrometer according to the seventh item, for example, a liquid chromatograph unit or the like can be placed on the upper part of the mass spectrometer. Thereby, the installation space of the liquid chromatograph mass spectrometry system as a whole can be reduced.

(Item 8) In the mass spectrometer according to any one of items 1 to 7, the fixing band may be made of an elastic member.

According to the mass spectrometer according to the item 8, even if the rod holder or the cell body fixed by the fixed band undergoes a shape change due to thermal expansion, the fixed band itself absorbs the shape change. Therefore, it is possible to securely fix the rod holder and the cell body to the pedestal while preventing damage to the rod holder and the cell body. In particular, if phosphor bronze having good thermal conductivity is used as the elastic member, heat from the rod holder and the cell body can be efficiently dissipated, and their heating can be suppressed.

(Item 9) In the mass spectrometer according to the second item, it is assumed that the fixed band is in surface contact with at least the outer peripheral surface of the portion between the rod electrodes adjacent to each other in the circumferential direction in the rod holder. Can be done.

According to the mass spectrometer according to the ninth item, since the fixing band comes into contact with the portion of the rod holder that generates the most heat, the heat of the rod holder can be satisfactorily dissipated.

1 ... Mass spectrometer 2 ... Column oven unit 3, 4 ... Liquid feeding unit 5 ... Injection unit 10 ... Vacuum chamber 10a ... Side lid 10c ... Left side wall 10d ... Locking part 10e ... Rear wall 10f ... Mounting hole 11 ... First Intermediate vacuum chamber 12 ... Second intermediate vacuum chamber 13 ... High vacuum chamber 14 ... Ionization chamber 15 ... Ionization probe 16 ... Degasket tube 17 ... First ion guide 18 ... Skimmer 19 ... Second ion guide 20 ... Lens electrode 21 ... Four Multipolar mass filter 211 ... Main rod electrode 212 ... Rod holder 213 ... Fixed band 214 ... Screw 22 ... Ion detector 30 ... Exterior cover 30a ... Right side cover 31 ... Circuit unit 32 ... Vacuum pump unit 33 ... Pedestal 33a ... Recess 35 ... Ion gauge 35a ... Connection pipe 350 ... First plate-shaped member 351 ... 357 ... Spacer 352 ... Bolt 353 ... Flange 354 ... Gasket retainer 355 ... Gasket 356 ... Second plate-shaped member 358 ... Screw 40 ... Front quadrupole Mass filter 41 ... Collision cell 410 ... Cell body 411 ... Rod electrode 42 ... Rear quadrupole mass filter C ... Ion optical axis

Claims (9)

A vacuum chamber in which a vacuum chamber is formed and one of the left and right sides can be opened and closed across the ion optical axis in the vacuum chamber.
An ion optical element that performs a predetermined operation on the ions derived from the sample,
A pedestal portion arranged on the bottom surface of the vacuum chamber and on which the ion optical element is placed,
A thin plate-shaped fixing band for sandwiching at least a part of the ion optical element between the pedestal portion and fixing the ion optical element so as to be pressed against the pedestal portion.
A band locking portion for locking one end of the fixing band provided inside the side wall surface of the vacuum chamber opposite to the openable / closable side surface of the vacuum chamber.
A band fixing portion for fixing the other end of the fixing band to the pedestal portion, which is provided on the openable side surface side of the vacuum chamber in the pedestal portion.
A mass spectrometer. The ion optical element is a quadrupole mass filter including four rod electrodes arranged around a linear axis and a rod holder made of an insulating material that holds the four rod electrodes. The mass spectrometer according to claim 1, wherein the fixing band is attached so as to press the rod holder against the pedestal portion. The ion optical element is a collision cell including a cell body portion for dissociating ions, and the fixing band is attached so as to press the cell body portion against the pedestal portion, according to claim 1. Mass spectrometer. The mass spectrometer according to claim 2, wherein the distance between the inside of the top surface of the vacuum chamber and the upper surface of the pedestal portion is larger than the outer diameter of the rod holder which is annular. The mass spectrometer according to claim 3, wherein the distance between the inside of the top surface of the vacuum chamber and the upper surface of the pedestal portion is larger than the outer diameter of the cell body portion having a cylindrical shape. The mass spectrometer according to any one of claims 1 to 5, wherein the vacuum chamber is arranged so that its openable side surface faces the side surface of the exterior cover. The mass spectrometer according to any one of claims 1 to 6, wherein a flat portion on which another device can be placed is formed on the upper surface of the exterior cover. The mass spectrometer according to any one of claims 1 to 7, wherein the fixing band is made of an elastic member. The mass spectrometer according to claim 2, wherein the fixed band is in surface contact with at least the outer peripheral surface of a portion of the rod holder between rod electrodes adjacent in the circumferential direction.

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